Western states and cities are more reliant on drinking water from U.S. Forest Service lands than previously known.
A first-of-its-kind study by the Forest Service reveals how some of the largest public water systems in the country rely on surface waters from the federal agency’s land. The agency plans to use the new data to help public water systems plan for a future of higher demand, development and climate change.
Previous studies have attempted to measure the amount of surface water moving directly from national forests and grasslands into public water systems, but the latest study from the agency includes measures of how much surface water from its lands are moved by pipe and canal networks to major cities nationwide.
The study revealed that about 90% of people in the West served by public drinking water systems rely on water from national forests and grasslands, sometimes transported hundreds of miles from points of origin to flow into taps.
In the East, most surface waters that end up in public drinking water systems begin in private forests.
Portland relies on the Bull Run Watershed for more than 90% of its drinking water. The Forest Service owns about 94% of that watershed 25 miles east of the city, along with about one-quarter of all the land in Oregon.
The agency manages 193 million acres of forests and grasslands nationwide. More than 80% of that land is in the West.
More than 136 million people nationwide rely on surface water from Forest Service lands for some portion of their drinking water, according to the report.
Although land and waters within Forest Service boundaries can be used for mining, logging and irrigation, the agency is also tasked with sustaining and improving water resources by protecting and restoring national forests and grasslands.
The study’s authors wrote that the new data can help state and federal agencies and the forestry industry develop better conservation and management plans responsive to climate change, population growth, land development and other threats to water supplies.
Across the country, there is greater demand for water as population and food production increase and climate change creates uneven demand.
Since 1950, total annual water withdrawal in the U.S. has nearly doubled along with the country’s population, according to data from the U.S. Geological Survey and the Census Bureau.
Many drinking water utilities are increasingly looking at better forest management as a way to protect water quality and supply.
The researchers wrote that they also hope to draw attention to the need to preserve all forested lands in the U.S.
About one-third of the country is covered in forests, but studies predict this will decline as population continues to grow, according to the report.
“A century of research has demonstrated unequivocally that forested lands provide the cleanest and most stable water supply compared to other land types,” researchers wrote.